Current female sterilization procedures often make use of implants that are placed within the fallopian tubes. For example, the Adiana® Permanent Contraception procedure (Hologic, Inc., Marlborough, Mass.) is a minimally invasive procedure in which a delivery catheter is passed through the vagina and cervix and into the uterus. A low level of radiofrequency energy is delivered to a small section of each fallopian tube to create a superficial lesion. A small implant is then placed within each fallopian tube at the location where the lesions were created. Over a period of time, tissue grows into and/or around the implants leading to complete occlusion of the fallopian tubes to thereby provide the desired sterilization. Such implants and procedures are described, for example, in U.S. Pat. No. 7,220,259, which is incorporated herein by reference.
Implants are placed within the fallopian tubes using minimally-invasive devices such as delivery catheters designed to be inserted into the patient's uterus and into the fallopian tubes. Such catheters are preferably inserted in conjunction with a hysteroscope to visualize implant placement. Conventional implant deployment mechanisms for tubal implants may make use of viscous-fluid damper assemblies. Such systems are used to limit the peak velocity at which the implants are delivered from the delivery catheter into the patient's body. It is often desirable, however, to deploy the implant quickly so that its position is not compromised during the delivery thereof. It is also preferred to deliver the implant at a substantially constant velocity over the entire delivery process. The use of conventional damper assemblies, while effective to prevent implant delivery at too high a velocity, may result in a delivery velocity that varies (i.e., decreases) during the delivery procedure, and a procedure time that is longer than optimal.
It is an object of the present invention to provide devices and associated methods that facilitate rapid implant deployment at a substantially constant velocity.